In diseases such as muscle pain, endometriosis, scleroderma and psoriasis, in vivo events occurring during clinical inflammation are unknown. In collaboration with investigators within the Rehab Medicine Division of the CC and the Reproduction Endocrinology Branch of NICHD, we have designed and fabricated a minimally invasive sample procurement needle based on a 32-gauge acupuncture needle. This static sampling needle is capable of obtaining tissue fluid samples from a defined anatomical site, such as skin or muscle, while causing no further discomfort than that associated with acupuncture. The needle, based on a standard Japanese-style acupuncture needle, has a 50-micron diameter laser-drilled hole approximately 0.2 mm from the tip. This hole is filled with lyophilized hydrogel. Once the needle is placed in the tissue, the gel rehydrates, drawing local tissue fluid into the gel. The needle is extracted and the gel is removed and placed into immunoaffinity capillary electrophoresis capillaries for further analysis. The major advantage of this apparatus is that multiple samples can be obtained with minimal discomfort to the patient. Additionally, modification with a depth gauge can accurately place the needle tip into the desired target tissue, thus ensuring that sampling occurs within a defined anatomical region. In addition to human samples, the needle has potential for recovering tissue samples from animals.